Add workflow to update backend dependencies automatically

.github/workflows/update-backend-dependencies.yml

@@ -0,0 +1,32 @@
+# GitHub Workflow to update pdm backend dependencies using Dependabot
+#
+
+name: Update dependencies
+
+on:
+  schedule:
+    - cron: "0 0 * * *"
+
+jobs:
+  update-dependencies:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Update dependencies
+        uses: pdm-project/update-deps-action@main
+        with:
+            token: ${{ secrets.GH_TOKEN }}
+            commit-message: "chore: Update pdm.lock"
+            # The PR title
+            pr-title: "Update dependencies"
+            # The update strategy, can be 'reuse', 'eager' or 'all'
+            update-strategy: reuse
+            # The save strategy, can 'compatible', 'wildcard', 'exact' or 'minimum'
+            save-strategy: minimum
+            # Ignore the version constraint of packages in pyproject.toml
+            unconstrained: false
+            # Whether to install PDM plugins before update
+            install-plugins: "false"
+            # Whether commit message contains signed-off-by
+            sign-off-commit: "false"